The process and advantages of gasifying hydrocarbonaceous material into synthesis gas are generally known in the industry. In high temperature gasification processes, a hot partial oxidation gas is produced from hydrocarbonaceous fuels, for example coal, oils, hydrocarbon wastes, and the like. In these processes, the hydrocarbonaceous fuels are reacted with a reactive oxygen-containing gas, such as air or oxygen, in a gasification reactor to obtain the hot partial oxidation gas.
In the reaction zone of a gasification reactor, the hydrocarbonaceous fuel is contacted with a free-oxygen containing gas, optionally in the presence of a temperature moderator. In the reaction zone, the contents will commonly reach temperatures in the range of about 1,700.degree. F. (930.degree. C.) to about 3,000.degree. F. (1650.degree. C.), and more typically in the range of about 2,000.degree. F. (1100.degree. C.) to about 2,800.degree. F. (1540.degree. C.). Pressure will typically be in the range of about 1 atmosphere (100 Kpa) to about 250 atmospheres (25,000 KPa), and more typically in the range of about 15 atmospheres (1500 Kpa) to about 150 atmospheres (1500 KPa).
In a typical gasification process, the hot partial oxidation gas will substantially comprise hydrogen, carbon monoxide, and lessor quantities of water, carbon dioxide, hydrogen sulfide, carbonyl sulfide, ammonia, and nitrogen.
The partial oxidation process in a free-flow, down-flowing vertical refractory lined steel pressure vessel is known. An example of such a process and pressure vessel are shown and described in U.S. Pat. No. 2,818,326, which is hereby incorporated by reference.
This refractory barrier is made of any suitable refractory material, i.e., alumina, chromia, magnesia, or mixtures thereof. This refractory brick is exposed to the gasification zone. For feedstock that has significant quantities of slag, i.e., greater than about 0.1 percent by weight of total feed, then refractory bricks are preferably constructed of more slag-resistant refractory material such as high chromia, magnesia, or mixtures thereof. Particulate carbon, ash, and/or molten slag typically containing species such as SiO.sub.2, Al.sub.2 O.sub.3, and the oxides andoxysulfides of metals such as Fe and Ca are commonly produced during gasification of certain feedstock.
In many applications the fuel contains significant quantities of ash and slag. At gasification temperatures the ash and slag may be partially or fully molten. It is generally preferred to keep the ash and slag in the molten state until it leaves the gasification reactor. Otherwise, particulate matter can accumulate and plug the reactor. However, this molten ash and slag, is very harsh to surfaces it contacts. The molten ash and slag attacks refractory brick, and this brick needs to be periodically replaced.
The refractory barriers, as well as burners, coolers, and instrumentation, have short life spans in the environment present in a gasification process, particularly in the presence of molten slag. The environment is very severe on non-refractory materials. An unprotected thermocouple left in this environment is rendered useless by corrosion in as little as ten minutes.
What is needed is a method to economically remove ash-forming materials from gasifier feedstock.